Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Debate Wisdom of Plan to Save Venice From Flooding

10.05.2002


The Italian government recently decided to move forward with planning for the construction of underwater, mobile floodgates to mitigate flooding in Venice, situated on islands in a lagoon in the Adriatic Sea. The soundness of the plan is discussed by several scientists in the May 14 issue of Eos, published by the American Geophysical Union.



The approved plan to protect Venice, called MOSE (Modulo Sperimentale Elettromeccanico, or Experimental Electromechanical Module), involves the construction of 79 gates at three lagoon inlets. When waters rise 1.1 meters [43 inches] above "normal," air will be injected into the hollow gates, causing them to rise, blocking seawater from entering the lagoon and thereby preventing the flooding of Venice. The floodgates will take approximately eight years and $2.6 billion to construct.

Some critics of MOSE, such as Paolo Antonio Pirazzoli of the French Centre National de la Recherche Scientifique (CNRS), are skeptical as to whether the gates will actually prevent flooding. In his Eos article, Pirazzoli states that the design of the gates is based on outdated predictions of sea-level change, utilizing a scenario that differs by nearly 0.26 meters [10 inches] from recent estimates of rise in sea level over the next century, made by the Intergovernmental Panel on Climate Change (IPCC). Pirazzoli also
asserts that the MOSE designers did not consider sea-level rise associated with land subsidence or increased water levels associated with extended rainy or windy periods.



Pirazzoli argues that once sea-level rise exceeds 0.31 meters [1 foot], possibly within the next 100 years, MOSE will become obsolete and will need to be replaced with watertight gates. Therefore, Pirazzoli contends, the Italian government should follow "soft" techniques, such as raising street level elevations, and await further assessment of sea-level rise to find "an updated, wise solution, more able to cope with foreseeable sea-level change."

In the same issue of Eos, MOSE supporters Rafael L. Bras, Donald R.F. Harleman, and Paola Rizzoli of the Massachusetts Institute of Technology, comment on Pirazzoli`s view. The writers, who worked on the design and assessment of MOSE, state that the gates will indeed be effective barriers to flooding. They note that the sea-level rise scenario they utilized was based on recent research and that the floodgates are designed to prevent flooding in the event of a 0.3 to 0.5-meter [12 to 20 inch] rise in sea level. Furthermore, they say, it is not necessary to consider further land subsidence, because it was the result of groundwater removal that was ended in the 1970s, and it has not been a problem since then.

Bras and his colleagues note that as flooding occurs with greater frequency, steps will have to be taken to protect the city, and the cost of doing nothing may be greater than the cost of constructing the MOSE gates. They believe that, "the barriers, as designed, separate the lagoon from the sea in an effective, efficient and flexible way, considering present and foreseeable scenarios." With regard to Pirazzoli`s contention that the mobile floodgates would eventually have to be replaced with watertight gates, they respond that if water levels continue to rise, the gates would just remain closed more often, in effect serving as "permanent" barriers.

Environmentalists argue, however, that keeping the gates closed for increasingly longer periods of time could be detrimental to the lagoon`s ecosystem, which relies on exchange of waters between the lagoon and the Adriatic Sea to flush pollutants from the lagoon. Without this cleansing flow, they say, toxic substances may build up in lagoon waters, damaging its delicate ecosystem.

In order to understand how frequent closing of the gates would impact the lagoon`s ecosystem, it is necessary to understand water flow patterns and exchange rates through the lagoon inlets. Miroslav Gacic and colleagues have taken preliminary steps in addressing these issues. Their research, published in the same edition of Eos, is based on a series of ship-borne surveys of water flowing through the inlet over an approximately forty-five day period.

Although the results are preliminary, the authors conclude that flow through the inlets is controlled primarily by tides. They also determine that the lagoon waters have an exchange rate of about one day, meaning that the lagoon is well-ventilated and quickly flushed. The researchers note that better assessments will be made when data representing several seasons become available.

Harvey Leifert | alphagalileo

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>